For assembling e.g. electronic systems, depending on the application, a greater or lesser number of modules are attached or fastened e.g. side by side to a mounting rail fixed inside a control cabinet, for example. Here a top edge of the module is first clipped over and the lower edge of the module is latched to the mounting rail by a swiveling movement, thereby securing said module in its final position. Such a module is disclosed in EP 0 740 499 A1.
During positioning of the modules, the modules are contacted to one another via a backplane or via connecting terminals or other such means. To ensure that all the contacts are maintained even under industrial conditions such as vibration, impact, dust, heat, cold, etc., a reliable fixing system is required. When a module is clipped to a mounting rail by means of a snap-on hook, it is disadvantageous that the snap-on hook, in order to ensure its rear latching functionality, has to have a degree of play between a lug and the mounting rail. If this play is not present, the snap-on mechanism will not work. However, as result of this play, in the case of a correctly dimensioned snap-on hook there is insufficient contact pressure between the module and the mounting rail in the latched state, which is undesirable for use under industrial conditions.
A solution using a retaining arm as disclosed in DE 102 43 383 B3 also has this drawback.
Even in a solution in which a screwed connection is used instead of the snap-on hook, it is disadvantageous that several full turns are necessary for actuating the screw and the fitter requires more time for assembly.
EP 0 528 341 B1 discloses a device for detachably fixing an apparatus housing to a mounting rail. With this device, a locking part is coupled to a clamping part such that a distance between the two sections can be changed by sliding the locking part into at least two positions, and that in one of said positions the clamping part is locked by the locking part such that it cannot be pushed into the opening position for detaching the apparatus housing from the mounting rail. Although this creates a device of relatively simple design, said device providing an easily detachable fixing for the housing, contact pressure between the module and the mounting rail cannot be achieved with this device.